New data has been added to global temperature records, which now indicate that the world has warmed even more in the last decade than previously thought.
Adding the Arctic
Researchers from the Met Office Hadley Centre and the Climatic Research Unit (CRU) at the University of East Anglia have updated HadCRUT, a global temperature set, to include data from weather stations in the Arctic, a region which has experienced one of the greatest levels of warming. The results have been published in the Journal of Geophysical Research.
Analysis of the new data within HadCRUT, one of just three global temperature sets and one which dates back to 1850, reveals that the world is warming even more than previously thought. The dataset, now known as HadCRUT4, indicates that between 1998 and 2010, temperatures rose by 0.11 degrees Celsius, which is 0.04 degrees more than previously estimated.
A change in the top spot
The new data has also led to a re-ordering of the hottest years on record, and HadCRUT4’s information is now more in line with the two other global records, held by NASA and the National Oceanic and Atmospheric Administration (NOAA) in the USA.
Prior to the update, HadCRUT placed 1998 as the hottest year on record, followed by 2010, 2005, 2003 and 2002. The addition of the new data now puts 2010 in the lead, followed by 2005, 1998, 2003 and 2006.
Despite these changes, the main conclusions of the temperature series have not altered; the dataset still indicates that, since 1850, an overall warming of 0.75 degrees Celsius has occurred, with the 10 warmest years on record all being in the last 14 years.
A necessary revision
Phil Jones, the director of CRU, explains that the update was required as previous data was not fully capturing changes in the Arctic due to a lack of data from the polar region, “For the latest version, we have included observations from more than 400 (observation) stations across the Arctic, Russia and Canada. This has led to better representation of what’s going on in the large geographical region.”
Fellow scientist Dr Peter Stott, Head of Climate Monitoring and Attribution at the Met Office, highlights the benefits of the update, and adds, “The scientific evidence is really strong that we are warming.”
Further alterations which have improved the reliability of the HadCRUT dataset include changes in the way in which sea surface temperature (SST) is recorded. Traditional methods of using buckets to collect sea water have been replaced by electronic sensors attached to ships, which can accurately record SST without introducing anomalies created through the use of different bucket types or due to the locations in which measurements were taken.
These improvements have allowed scientists to recalibrate and recalculate data, amending data collected in previous years.
“An example of this is the rapid change in the kinds of measurements we see in the digital archives around the Second World War,” explains Dr Stott. “Research has shown readings from buckets were generally cooler so when the database changes from one source to another, you see artificial jumps in the temperature. We have quantified these effects and corrected them, providing a clearer view of the evolution of global temperatures.”
Read more on this story at BBC – Update for world temperature data.
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Kathryn Pintus, ARKive Species Text Author